1. Field of Invention
The invention relates to a control of a valve train system of an internal combustion engine.
2. Description of Related Art
An exhaust gas recirculation system of an internal combustion engine is disclosed in Japanese Patent Application Laid-open No. JP-A-4-143449. This exhaust gas recirculation system allows exhaust gas to be admitted into a combustion chamber in an intake stroke. Since the exhaust gas as being inert has a heat absorbing function, the exhaust gas within the combustion chamber decreases the combustion temperature. This makes it possible to suppress generation of NOx in the combustion chamber. Accordingly, upon admission of the exhaust gas into the combustion chamber in the intake stroke in the exhaust gas recirculation system disclosed as above, generation of NOx may be suppressed.
The decrease in the combustion temperature of the combustion chamber may reduce the combustion efficiency. Therefore, more quantity of the fuel is required to cause the internal combustion engine to output the required torque.